U.H.D

I am pleased to report that the software is now working
with the new Universal Hardware Driver (UHD) from
Ettus Research. This will allow me to have much greater
control over the USRP2 + WBX from within the GUI.

System block diagram

This is the block diagram of the system. The bold text in the centre box
shows the parts of the system that have been implemented in the software.
The block diagram was drawn using free schematic software from PCBExpress.

Although using a USRP2 for Digital Television may appear expensive,
the USRP2 SDR can be re-programmed to implement virtually any type
of radio you desire. I consider it the best value radio I have ever bought.
The USRP2/WBX cost about the price of a new TS2000.

DVB Primitive GUI

Above is the first primitive GUI for the DVB-S transmitter.
The GUI is based on QT4. The visible tab is the one for the
various FEC rates available in DVB-S.

I now have direct control of the Hauppauge PVR500 card using
the v4l2 API. This is necessary as the video bitrate needs changing
when any of the parameters are changed like the FEC code rate.

Originally I wrote the program in standard C but to make it easier
for me to integrate with the GUI I have changed the files to C++.
The whole DVB transmitter can now be developed from within the
QT4 development environment. For someone that is not a Linux natural
(I have used Visual C++ before) being able to use a visual development
environment again is nice. I know I have just upset the Linux hardcore
but that is the way it is.

Before I can proceed much further with the development I need the
new UHD for the WBX board. This will allow me to control the
transmitters frequency from the GUI.

I will probably finish off the 1.3 GHz PA next and will also have a think
about the GUI layout. Eventually I want to add DVB-T and when I have
figured out how best to do it, DVB-S and DVB-T receive.

Still no cigar

The SI tables are still not working. I have a set of SI tables provided by
Rob M0DTS and they work.

I have code that provides identical tables, same contents, checksums etc
and they don't work. Obviously I am missing something. I will figure it
out eventually.

On the theme of GUIs I have decided to use QT4 developed by Trolltech
(now owned by Nokia). http://qt.nokia.com/ I am setting up the
development environment as I type so more on that later.

I have also been looking at all the DVB applications available for Linux.
I just wish I knew what they all did. Hopefully down the line it will be possible
to add receive support to my software using a suitable Linux tool.
I will have to do the demodulator but once I have the program stream extracted
it should be possible to feed that to a 3rd party tool for display.

I am ramping up my enthusiasm for the new UHD (Universal Hardware Driver)
from Ettus Research http://www.ettus.com/

This will allow cross platform support for their products. It will also allow closer
integration between my code and the USRP2. Currently no support for the WBX
transceiver board I use exists but it is coming. So watch this space.

I am always keen to hear from anyone reading this Blog, if you have any
comments, criticisms, advice or questions please contact me, I don't byte.